JPH07108053B2 - Filter device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial application] The present invention relates to a filter device that superimposes two kinds of different frequency signals indicating the state and status of a load side (signal generator side) on an AC signal of a distribution system. Regarding

[Prior Art] Generally, in a power distribution system, when an accident or a failure occurs in each load, it is necessary to centrally manage the location of the accident or the failure and to promptly deal with the accident or the failure. Yes, conventionally, receiving a signal generator for each load, laying a signal line between each signal generator and the management device separately from the distribution line,
Through this signal line, signals indicating the state and status of each load side of the system are transmitted to the management device.

In this case, since a large number of signal lines are required in addition to the distribution line, the number of signal lines to be laid is large, which is expensive, and laying is troublesome.

Therefore, so-called frequency shift communication (FSK communication) may be used for signal transmission by the distribution line carrier method, which is different.
The frequency signals of different types are respectively associated with logic "1" and "0", and a signal obtained by combining both frequency signals and encoding is transmitted to the management device via a distribution line.

In the signal transmission of this FSK communication, since both frequency signals are superimposed on the commercial AC signal of the distribution system, various filter devices have been conventionally considered.

This conventional filter device is constructed as shown in FIG. 3 or FIG.

In FIG. 3, 1 is a commercial power source such as a substation for supplying a commercial AC signal, 2a and 2b are a pair of distribution lines of a power distribution system that connects the power source 1 and each load, and 3 are different. It is a signal generator that selectively generates two types of frequency signals in a constant cycle.

4a and 4b are two switches, one ends of which are both connected to one end of the generator 3 so that when one switch 4a or 4b is turned on, the other switch 4b or 4a is turned off by a control means (not shown). The control means is controlled and operates according to the switching of the oscillation frequency of the generator 3.

5a and 5b are two resonance capacitors each having one end connected to the other end of each of the switches 4a and 4b, and 6a and 6b are two resonance reactors each having one end connected to each of the other ends of the capacitors 5a and 5b. And the other ends are both connected to one distribution line 2a.

Reference numeral 7a is a series resonance circuit formed by the capacitor 5a and the reactor 6a, and 7b is a series resonance circuit 7b formed by the capacitor 5b and the reactor 6b.

The other end of the generator 3 is connected to the other distribution line 2b.

Next, the filter device shown in FIG. 4 is formed into a circuit configuration called a Jaumann circuit, and in FIG. 4, 8 is a primary coil.
A coupling transformer having 8a and a secondary coil 8b.
Both ends of the next coil 8a are connected to both ends of the signal generator 3. 9a and 9b are two resonance capacitors, one end of which is connected to one end and the other end of the secondary coil 8b, and 10a and 10b are two resonance reactors, one end of which is the other end of the capacitors 9a and 9b, respectively. And the other ends thereof are both connected to one of the distribution lines 2a.

Reference numeral 11a is a series resonance circuit formed by the capacitor 9a and the reactor 10a, and 11b is a series resonance circuit formed by the capacitor 9a and the reactor 10b.

The secondary coil 8b has an intermediate tap t connected to the other distribution line 2b.

In addition, the capacitances and the inductances in FIGS. 3 and 4 are
The resonance frequencies of the series resonance circuits 7a and 11a are set to f1, and the resonance frequencies of the series resonance circuits 7b and 11b are set to f2.

When 1/2 of one cycle (= T) of the commercial AC signal from the power source 1 shown in FIG. 5 (a) becomes the cycle of switching the oscillation frequency of the generator 3, for example, FIG. As shown in, the frequency signal S1 of the frequency f1 and the frequency f2 from the generator 3
Considering the case where the frequency signal S2 of (<f1) is sequentially output for each T / 2 time, in the device of FIG. 3, the switch 4a is turned on and the switch 4b is turned on by the control means in the first half of T / 2 time.
Is turned off, and both switches 4a are turned off and the switch 4b is turned on by the control means in the latter half of T / 2.

Therefore, the frequency signal S1 of the first half T / 2 time is superimposed on the commercial AC signal via the series resonance circuit 7a of the resonance frequency f1, and the frequency signal S2 of the second half T / 2 time is the resonance frequency f2.
Is superimposed on the commercial AC signal via the series resonance circuit 7b, and as a result, a signal having a waveform as shown in FIG. 5C is transmitted via the distribution lines 2a and 2b.

On the other hand, in the same case as described above, in the device of FIG. 4, the frequency signals S1 and S2 that switch from the generator 3 at the cycle of T / 2 are the series resonance circuit 11a having the resonance frequency f1 and the series resonance circuit having the resonance frequency f2. A signal having a waveform shown in FIG. 5 (c) is transmitted via the distribution lines 2a and 2b by being superimposed on the commercial AC signal via each of the circuits 11b.

At this time, the frequency signal S1 of frequency f1 is set to logic "1", frequency f
It is possible to transmit a signal having a predetermined bit content by combining the frequency signal S2 of 2 with a logic "0" and combining the frequency signals S1 and S2. In the management device, the bit of the transmitted signal can be transmitted. By demodulating and reading the contents, the state and status of the transmitting side (each load side) can be known.

For example, when the signals S1, S2, S1, S2, S2, S1 are sequentially generated and transmitted at a constant time of T / 2, the management device displays “101001
A signal with the content of "is received.

[Problems to be Solved by the Invention] In the case of the filter device of FIG. 3, the control means performs switching control of the switches 4a and 4b in accordance with the frequency signals S1 and S2 to select (switch) the filter. Although the signals S1 and S2 can be reliably transmitted through the series resonance circuits 7a and 7b, respectively, two switches 4a and 4b and a control means for controlling these switching are required, and further, both switches 4a and 4b respond. However, there is a problem in that noise is increased due to the disturbance caused when the switches 4a and 4b are switched.

Further, in the case of the filter device shown in FIG.
The leakage component from the distribution system side due to the capacity difference between a and 9b wraps around to the generator 3 side, and the circulating current due to the capacity difference flows through both series resonance circuits 11a and 11b and is superimposed on the distribution lines 2a and 2b. There is a problem that the circulating current is added to the currents of the frequency signals S1 and S2, and the generator 3 side and the distribution system side adversely affect each other.

The present invention has a simple structure to convert an AC signal in a distribution system into an AC signal.
It is an object of the present invention to enable efficient and accurate superposition of types of frequency signals.

[Means for Solving the Problem] In order to achieve the above object, the filter device of the present invention selectively generates two different types of frequency signals to be superimposed on an AC signal of a power distribution system in a constant cycle. A signal generator, a primary side series resonance circuit formed by connecting in series a resonance first capacitor and a primary coil of a coupling transformer between both ends of the signal generator, and one end of one distribution line of a distribution system A transformer secondary coil connected to the transformer, and a transformer coupling coefficient adjusting reactor, a resonance second capacitor and a resonance resistor between the other end of the secondary coil and the other distribution line of the distribution system. And a secondary side series resonance circuit formed by connecting in series.

[Operation] In the case of the filter device of the present invention configured as described above,
By adjusting the inductance of the coupling coefficient adjusting reactor of the secondary side series resonance circuit and the coupling coefficient of the coupling transformer, the primary side series resonance circuit and the secondary side series resonance circuit form a transformer-coupled multiple resonance circuit. , The two resonance frequencies of the multiple resonance circuit respectively match the frequencies of the two kinds of frequency signals from the signal generator, so that both frequency signals generated alternately from the signal generator at constant intervals are efficient and accurate. And is superposed on the AC signal of the distribution system.

At this time, the conventional filter selection switch and control means are not required, the configuration is simple and inexpensive, and the coupling transformer separates the primary side and the secondary side. Therefore, the conventional Jaumann circuit is used. In this case, the influence between the distribution system side and the signal generator side due to the capacitance difference of the capacitor can be prevented.

[Embodiment] An embodiment will be described with reference to FIGS. 1 and 2.

First, an equivalent circuit diagram of the basic circuit configuration of the present invention is as shown in FIG. 2 (a), and signal generation for selectively generating two types of frequency signals S1 and S2 at a constant cycle of T / 2, for example. Bowl 3
Between both ends of the generator, the internal impedance 12 of the generator 3 etc., the resonance first capacitor 13 and the primary coil of the coupling transformer 14
Primary side series resonance circuit 15 is formed by connecting 14a in series,
A secondary side resonance circuit is formed by connecting a series circuit of a resonance second capacitor 16 and a resonance resistor 17 between both ends of the secondary coil 14b of the transformer 14.

Then, the impedance 12 and resistance 17 values are set to R1 and R2, respectively.
1, the capacity of the second capacitor 13, 16 is C1, C2, the primary coil
If the inductances of 14a and secondary coil 14b are L1 and L2,
The resonance frequency fa of the primary side series resonance circuit 15 is Similarly, the resonance frequency fb on the secondary side of the transformer 14 becomes Becomes

Further, when fa = fb = fr, (fr is the center frequency of resonance), the circuit shown in FIG. (M is a mutual inductance of the transformer 14), and a transformer-coupled multiple resonance circuit having two resonance frequencies represented by the following equation is obtained.

By appropriately adjusting the coupling coefficient k, the resonance frequencies f'and f "in the above equation can be made to match the frequencies f2 and f1 of the frequency signals S2 and S1 of the signal generator 3, respectively.

By the way, it is generally not easy to design the transformer to change the coupling coefficient k.

For example, the frequency fr is 450Hz, and one resonance frequency f'is 435H.
In order to obtain z, from the above equation, the coupling coefficient k must be a coarse coupling value of k = (fr / f ′) ² −1 = (450/435) ² −1≈0.07, that is, the value of the air-core reactor. I won't.

On the other hand, the inductances L1 and L2 for obtaining a resonance frequency of about 450 Hz are usually about 10 ^-3 H, which is the value of a transformer with an iron core.

And the coupling coefficient of a transformer with an iron core is generally 0.
It is 9 or more, and it is difficult to set the above-mentioned coarse coupling value to about 0.07 from the viewpoint of manufacturing, and the loss is large and the efficiency is poor even when it is used.

Therefore, in the present invention, as shown in FIG. 2B, the coupling coefficient adjusting reactor 18 of the transformer 14 is inserted in the secondary side resonance circuit, and the secondary side including the reactor 18, the second capacitor 16 and the resistor 17 is inserted. The series resonance circuit 19 is configured so that the coupling coefficient of the transformer 14 can be easily adjusted by the inductance L3 of the reactor 18.

When the inductance of the secondary coil 14b of the transformer 14 of FIG. 2 (b) is L2 ′, the inductance L3 is set so that the inductance L2 satisfies L2 = L2 ′ + L3 in the circuit of FIG. 2 (a). Set.

At this time, the coupling coefficient of the transformer 14 in FIG.
Then, the relation between this coupling coefficient k ′ and the coupling coefficient k of the transformer 14 in FIG. Then, it becomes the following formula.

Therefore, the coupling coefficient k'of the transformer 14 in FIG.
Is 0.9 and the coupling coefficient k after adjustment by the inductance L3 of the reactor 18 is 0.07 of the coarse coupling value, first, the inductance L2 ′ is changed to L2 ′ from the above equation.
= (K / k ') ² L2 = (0.07 / 0.9) ² L2 ≈ 0.06 L2, and the inductance L3 can be calculated by the relationship of L2 = L2' + L3.
You can set it to the size of the following formula.

L3 = L2-L2 '= L2-0.06L2 = 0.94L2 ... Then, the equivalent circuit diagram in the state of being actually connected to the distribution system is as shown in FIG.

That is, when the equivalent impedance of the distribution lines 2a and 2b in FIGS. 3 and 4 is represented by the resistor 20 and the reactor 21, as shown in FIG. 1, the secondary side series resonance circuit 19 of FIG. 22a, which is the other end of the secondary coil, and terminal 22 which is the other end of the secondary coil 14b
A resistor 20 and an inductance 21 are connected in series with b.

Then, set the inductance of reactors 18 and 21 in Fig. 1 to L
If 3 ', L4 and the values of the resistors 17, 20 are R2', R3, the inductances L3 ', L4 and the inductance L3 of the reactor 18 in Fig. 2 (b) satisfy L3 = L3' + L4, Similarly, the resistance values R2 ′, R3 and the resistance value R2 of the resistor 17 in FIG.
= R2 '+ R3 is satisfied.

At this time, the inductance L4 and the resistance value R3 can be derived by calculating the equivalent impedance of the distribution system, and the inductance L3 'of the reactor 18 in FIG.
3 ′ = L3−L4 can be determined by applying L3 according to the above equation and known L4, and the resistance value of the resistor 17 can also be R2 ′.
= R2-R3 can be determined by applying known R2 and R3 to the formula, and by these determinations, the generator 3 determines the resonance frequencies f ', f "of the filter device having the multiple resonance circuit configuration of FIG. The frequencies f2 and f1 of the generated frequency signals S2 and S1 are made to coincide with each other so that both frequency signals S1 and S2 from the generator 3 can be superposed efficiently and accurately.

Then, the frequency signal generated by the generator 3 is selectively switched to the signals S1 and S2 at a constant cycle according to the content of the code to be transmitted, and, for example, the signals S1, S2, and S1 are generated at fixed intervals of T / 2. , S
When 2, S2, S1 are sequentially generated and transmitted, the management device receives a signal of "101001" as in the case of the conventional device.

At this time, the conventional filter selection switch and control means are not necessary, the configuration is simple and inexpensive, and the transformer 14 separates the primary side and the secondary side from each other. It is possible to prevent the influence between the distribution system side and the signal generator side due to the difference in capacitance of the capacitors.

[Advantages of the Invention] Since the present invention is configured as described above, it has the effects described below.

By adjusting the inductance of the coupling coefficient adjusting reactor 18 of the secondary side series resonance circuit 19 and the coupling coefficient of the coupling transformer 14, the primary side series resonance circuit 15 and the secondary side series resonance circuit 19 are transformer-coupled. A multi-resonance circuit is configured, and two resonance frequencies of the multi-resonance circuit match the frequencies of the two types of frequency signals that are alternatively output from the signal generator 3 in a constant cycle, and become the AC signal of the distribution system. The two types of frequency signals can be efficiently and accurately superposed, and at this time, the conventional filter selection (switching) switch and control means are not required, the configuration can be simplified, and the coupling transformer 14 can be achieved. By separating the series resonance circuits 15 and 19 on the primary side and the secondary side by means of, it is possible to prevent the influence between the distribution system side and the signal generator side.

[Brief description of drawings]

FIG. 1 is an equivalent circuit diagram of one embodiment of the present invention, and FIGS. 2 (a) and 2 (b) are explanatory views of the principle of the present invention, FIGS.
Each of the drawings is a connection diagram of a conventional example, and FIGS. 5A to 5C are various signal waveform diagrams for explaining the operation of FIG. 2a, 2b …… Distribution line, 3 …… Signal generator, 13 …… First capacitor, 14 …… Coupling transformer, 14a, 14b …… Primary and secondary coils, 15 …… Primary side series resonance circuit , 16 …… Second capacitor, 17 …… Resonance resistor, 18 …… Coupling coefficient adjusting reactor, 19 …… Secondary side series resonance circuit.

Claims (1)

[Claims] 1. Different two superposed on an AC signal of a distribution system.
A signal generator that selectively generates various types of frequency signals at a constant cycle, and a primary side formed by serially connecting a resonance first capacitor and a primary coil of a coupling transformer across the generator. A series resonance circuit, a secondary coil of the transformer whose one end is connected to one distribution line of the distribution system, and a coupling coefficient of the transformer between the other end of the secondary coil and the other distribution line of the distribution system. A secondary side series resonance circuit formed by connecting an adjusting reactor, a second resonance capacitor, and a resonance resistor in series.